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Keywords:

  • kinetics;
  • curing of polymers;
  • bismaleimide;
  • UV cure

Abstract

A novel and general kinetic rate equation combining ultraviolet-induced (UV-induced) curing and thermal curing was successfully derived from the conventional thermal-kinetic rate equation. This proposed novel kinetic rate equation can be applicable to the curing system either simultaneously or individually by UV-induced and thermal cure methods. This general kinetic rate equation is composed of the reaction order n, activation energy Ea, curing temperature T, energy barrier of photoinitiation EQ, intensity of UV radiation Q, concentration of photoinitiator [I], and a few other parameters. The proposed equation was supported by experimental data based on the curing systems of 4,4′-bismaleimidodiphenylmethane (BMI) and 2,2-bis(4-(4 maleimido phenoxy) phenyl propane (BMIP). The BMI and BMIP systems were isothermally cured at various temperatures, or simultaneously cured with varying intensity of UV radiation (wavelength 365 nm). Conversion levels for the various cured samples were subsequently measured with a FTIR spectrometer. The reaction order n = 1.2, activation energy Ea = 40,800 J/mol, and EQ = 7.5 mW/cm2 were obtained for curing BMI system. The reaction order n = 1.3, activation energy Ea = 53,000 J/mol, and EQ = 9.1 mW/cm2 were obtained for curing BMIP system. The values of n and Ea in the same curing system (BMI or BMIP) are irrespective of the curing method (either simultaneously or individually by UV-induced and thermal cure methods). The salient results of this study show that UV radiation only enhances the initiation rate and UV ration do not influence the activation energy Ea. The experimental results are reasonably well represented by these semi-empirical expressions.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010